Work based learning Dark-room poster

I was asked to create and come up with an idea or some sort of notice for the door before you enter the dark room as people are sometimes unaware of people processing film and could end up working in on someone wile the negatives or ilford paper it out and could result in the paper or negatives to be exposed at you don't want that to happen so to prevent this i come up with a poster for the door and this is what i come up with:

This is the picture I taken on my phone and I placed this in to photoshop and made a new canvas.

This is the first one I made and I thought a tight crop was good as it fitted the slide on the door but when I emailed kevin he told me to change the size to a4 but as it doesn't look right as its attached to my blog.